The course aims to examine all kinds of linguistic influence which affect the process and the degree of development in second/foreign language learning. It refers both to language similarities and differences and to what happens in a language learner’s mind during comprehension and production of the L2. Relevant topics such as contrastive studies, the role of the first language, the L2 learner’s linguistic system (interlanguage), simplification, avoidance, borrowing, code-switching, learners’ errors and their significance for language development, error correction, individual learner differences, etc. will be discussed and practical suggestions will be made. Assessment: Final exam. and optional research paper of about 3,000 words